Class 1 circuits and power circuits in same conduit

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ChargedUp

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Per NEC 725.48(B)(1), class 1 circuits and power circuits shall be permitted to occupy the same cable or raceway, only where the equipment powered is functionally associated. Per NEC 725.49(B), the insulation on the class 1 circuit shall be the same of the power circuit insulation -this corresponds with NEC 300.3(C)(1).

If a proposed installation requires 1000V rated power circuit, and the class 1 circuit can only be procured with a 600V rating, could installing the class 1 circuit in innerduct, within the same raceway as the power circuits, meet NEC intent? My understanding is NO, unless there was an innerduct out there with a 1000V rating. The electrical noise/interference from the 1000V rated power circuit may have an adverse affect on the 600V class 1 circuit.

Thoughts? Any ideas on how to mitigate this? Installing the power and comms in separate conduit is not a viable solution. Procuring 1000V rated comms is also not a viable solution.

Thanks
 
Is 1000V the system voltage for the power circuit? 725.49(B) and 300.3(C)(1) don't say the insulation ratings need to be the same, but that all of the insulation ratings for conductors in the same raceway need to be at least that of the highest voltage among those conductors.
 
Thank you for your reply. Yes, the system voltage for the power circuit is 1000V. Believe a thought process from other folks is putting the class 1 comms in innerduct, now puts it in a "separate conduit" within the same raceway that contains the 1000V power circuit - thus meeting NEC. I think main NEC intent is to prevent electrical noise, which installing in innerduct within the same raceway as the power circuit would not mitigate.
 
The intent of the NEC is definitely NOT to prevent electrical noise. NEC is not concerned with design issues such as noise. It's to prevent flashover from a high voltage source to an insufficiently rated insulated wire.
 
Yes, I would agree with that statement as well. That being said, what are your thoughts on this problem and how to mitigate? Do you see the only solution as installing 1000V rated comms, or would installing 600V rated comms in innerduct, within same raceway as 1000V power circuit, comply with NEC?
 
I don't have any experience with innerduct, but the NEC explicitly says what can be done, so if 725 circuits (as opposed to 770 or 800 circuits) were permitted in innerduct there would be mention of it. Innerduct is defined in Chapter 1 so there should be multiple references to it, but I've looked around for a bit but I can't find any.
 
No we cannot use fiber optic. Only CAT6. NEC 2020 Section 725.49 says that insulation shall be rated for the “system” voltage and not less than 600V... So is the communication "system" in this case whatever component the CAT6 is connecting to at either end? Or is the the "system" considered whatever the 1000V rated power conductors are connected to within same raceway as CAT6? i.e. the communication and power circuit is in the same raceway, but can the communication "system" be considered separate from the power "system"?

Only ask because NEC 2020 specifically says class 1 can occupy the same raceway as power "without a barrier", where they are functionally associated... Can we consider this a functionally associated 600V communication system and 1000V power system? Basically all CAT6 out there is only 600V rated, not 1000V. Was the NEC aware of this and allowed these different "systems" to occupy the same raceway "without a barrier" only where functionally associated?

If the the communication cable faults, the system will shutdown immediately, if the power cable faults, the system will shutdown immediately. Is voltage flashover a concern in this instance? Personally I would be more concerned with EMI, therefore a shielded CAT6...

Basically want simple yes or no's whether or not functionally associated 600V class 1 comms can share same raceway as 1000V power conductors, without a "barrier", and if that would be considered code compliant and meet intent of NEC.

Worth mentioning again, if a "barrier" is required, can innerduct fit this mold all things considered in paragraphs above... innerduct should be able to be considered a separate "raceway" and possibly even prevent voltage flashover...
 
Sorry if you already addressed this but Is the 1000V rating truly the system voltage or a required insulation rating from manufacturer or specs. For example DOT specs in my area require 2400V wiring.
 
CAT 6 would be Class 2 and not Class 1. You need to be looking in Part II of Article 725, not Part I where 725.49 is.
 
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